1. Field of the Invention
This invention relates to aluminum ionomers and more particularly it relates to melt processible aluminum ionomer blends.
2. Description of the Prior Art
Aluminum ionomer blends are useful where sodium or zinc ionomers cannot be used because of their temperature limitations. Sodium and zinc ionomers of ethylenically unsaturated carboxylic acid copolymers have no resistance to compression set at 70.degree. C. and at 70.degree.-100.degree. C. they loose all of their physical strength. Unlike these ionomers, aluminum ionomers maintain useful physical properties above 100.degree. C. However, neat aluminum ionomers are not melt processible using standard thermoplastic processing techniques, such as injection molding or extrusion.
Japanese Patent Publication No. 56-55442 discloses a resin composition having improved properties comprising an ionically crosslinked copolymer of ethylene and alpha,beta-ethylenically unsaturated carboxylic acid, partially or completely ionically crosslinked by metal ion optionally an alpha,beta-unsaturated ester, and a polyamide resin having a melting point of not more than 160.degree. C. Ten mole percent or more of the alpha,beta-unsaturated carboxylic acid component is disclosed to be substituted by Na.sup.+, Mg.sup.2+, Zn.sup.2+, Al.sup.3+, and the like. It is disclosed that the resin composition "can be prepared by a known blending method; the composition is processed into a powder, chips, pellets, or the like form followed by feeding to an extruder, injection molder, compression molding machine or the like to form films, sheets, tubes, molded articles, or the like." It is further taught that "It is permissible to directly feed to the above molding equipment the ionically crosslinked copolymer together with the polyamide resin in the form of a powder, chips, pellets, or the like." The examples disclose ionomers neutralized with magnesium, zinc and sodium ions.
U.S. Pat. No. 4,187,358 discloses a resin composition of (1) an aromatic copolyester derived from (a) a mixture of terephthalic and isophthalic acid and (b) a bisphenol, (2) a polyamide, and (3) an ionomer.
The ionomer is disclosed to be a base copolymer and the product obtained by reacting the base copolymer with a metal compound capable of ionizing the copolymer. The base copolymer is an alpha-olefin/alpha, beta-unsaturated carboxylic acid copolymer e.g., ethylene/acrylic acid copolymer, ethylene/methacrylic acid copolymer, ethylene/itaconic acid copolymer, ethylene/maleic acid copolymer, ethylene/methacrylic acid/vinyl acetate copolymer, ethylene/acrylic acid/vinyl alcohol copolymer, etc. As the metallic ion suitable for neutralizing the carboxylic acid group of the base copolymer metal ions of the groups IA, IB, IIA, IIB, and IIIA of the periodic Table are disclosed to be preferable, the metallic ions having an aromatic valence of 1 to 3 (e.g. Na.sup.+, K.sup.+, Li.sup.+, Cu.sup.2+, Be.sup.2+, Zn.sup.2+ and Al.sup.3+). The ionomer can be produced by reacting the base copolymer with a formate, acetate, hydroxide, methoxide, carbonate, etc. of the above metals. It is also disclosed that acidic olefinic copolymers that are not reacted with metallic ion can also be used. These are obtained by mixing the acidic olefinic copolymer with polyamide and the specified aromatic copolyester without adding metallic ion. It is further disclosed that it is also possible to form a resin composition by adding the metallic ion while melt extruding an acidic olefinic copolymer, a polyamide and/or specified aromatic copolyester, thus neutralizing the acidic olefinic copolymer.
The ionomer is disclosed to be a very soft substance with a heat distortion temperature measured by ASTM-D648 (18.6 kg/cm.sup.2) of below room temperature.
The examples only disclose ionomers neutralized with zinc and sodium ions.
It is disclosed that the resin composition can be prepared by mixing the three ingredients by any of the known methods e.g. kneading through a kneader or rollers or melt extruding through an extruder or finely pulverizing and mixing in a super mixer and then pressforming or rotational molding. It is further disclosed that the sequence in which the materials are mixed is optional i.e. three ingredients may be mixed at the same time or two of them mixed first and the third ingredient added later. In some cases, in order to obtain improved properties, it is preferable to melt mix the specified aromatic copolyester and polyamide first and mixing the resulting composition with an ionomer in the molten state or melt mixing the ionomer and the polyamide to form a composition and then mixing the resulting composition with the specified aromatic copolyester in the molten state.